When the above procedures are completed, patients start taking pioglitazone by mouth once a day for 48 weeks, keeping track of the medication and any side effects. They will be seen at the clinic every 2 weeks for the first month and then every 4 weeks for the rest of the treatment period. The visits will include an interview and examination by a physician and blood draw for laboratory tests. Female patients will have a pregnancy test at each clinic visit. At the end of the treatment period patients will be admitted to the Clinical Center for a repeat medical evaluation that will include the procedures described above.